Nearly 100% selectivity of photothermal CO2 reduction into CH4 achieved by Pt/Sr2Nb2O7 heterojunction

Developing efficient and highly selective photocatalytic CO2 reduction catalysts remains one of the most significant challenges in achieving carbon neutrality. Herein, the efficient conversion of CO2 to CH4 with selectivity close to 100% was achieved by loading uniformly dispersed Pt nanoparticles on the surface of Sr2Nb2O7 nanosheets; the optimal CH4 yield was as high as 15.65 μmol/g/h. Various characterizations demonstrate that Pt nanoparticles have a significant photothermal effect that can increase the catalyst surface temperature, and improve the performance and electron transport rate of the catalyst. Additionally, Pt nanoparticles and Sr2Nb2O7 nanosheets form heterojunctions, which facilitate the separation of photogenerated carriers and aggregation of photogenerated electrons on the Pt nanoparticles. Pt nanoparticles become new reactive sites that have a strong adsorption impact on the key intermediate ∗CO and reduce the reaction energy barrier of ∗CHO generation. The results revealed that the synergy between electron accumulation, strong adsorption of ∗CO, and reduction of the reaction potential of ∗CHO are the reasons for the efficient and selective conversion of CO2 to CH4. This work provides novel insights into the role of metal-based cocatalysts in selective CO2 photoconversion and new ideas for designing efficient CO2 conversion systems.